1. Technical Field
This invention relates generally to seal assemblies, and more particularly to rotary shaft seal assemblies.
2. Related Art
Shaft seals are commonly used throughout numerous types of vehicle applications. Aside from the shaft seal having a primary seal lip to establish a reliable seal against a running surface of a rotating shaft or wear sleeve, both to prevent the ingress of contamination and the egress of desirable lubrication, it is desirable to provide auxiliary seal lips to further prevent the ingress of contamination and the egress of desirable lubrication. Accordingly, it is known to construct a shaft seal having primary and auxiliary seal lips formed in a single operation and of the same material. Unfortunately, having to form the primary and auxiliary seal lips in a single operation and from the same material can come with drawbacks. For example, with the type of material being the same for both seal lips, the performance of one of the seal lips may be diminished in that the material may not be the optimal material for the particular seal lip. Further, if the seal lip material is costly, such as is often the case for auxiliary dust excluder seal lips, then economic inefficiencies may be incurred as a result of having to make the primary seal lip from the more costly material of the auxiliary seal lip. To resolve the problem of having to make the seal lips from the same material, it is further known to use separate operations to mold the separate seal lips from separate materials, with the separate seal lips ultimately being fixed in inseparable relation with one another with the seal assembly. This too comes with drawbacks of having to add potentially costly process operations to the manufacture process of the seal assembly. In addition, having a seal assembly with dedicated, integrally fixed seal lips typically limits the use of the seal assembly to a specific application, given the seal assembly is a single piece construction of inseparable components.